A cutterhead with water jet assist cutting uses the action of a high pressure water jet directed towards the tip of each cutting tool to reduce mechanical cutting forces, tool wear, dust production and risk of methane ignition. Tests have demonstrated that a maximum efficiency of the water jet action is obtained when the depth of the groove made by the jet equals the cutting depth of the cutting tool or is slightly inferior to it. The depth of the groove created by a waterjet is a function of the water pressure. Therefore, water pressure should vary in relation with the tool depth of cut.
Current state of the art has shown the development of water jet assist cutting technique to be limited by the reliability and maintainability of high pressure equipment, flexible hoses, valves, distributors, and rotating seals. Solutions to supply high pressure water to the operating cutting tools only, which is essential for safety purposes and for limiting the power requirements, are complex and their life expectancy is not satisfactory. Sectorial distribution should be easily and quickly modified when the cutting direction changes.
In addition to these technical problems, there is no current solution to adapt the water pressure to the variable cutting depth of the tools.